Fuel system for two-cycle internal combustion engines



Sept. 13, 1955 H. G. UPTON 2,717,584

FUEL SYSTEM FOR TWO-CYCLE INTERNAL COMBUSTION ENGINES Filed April 27, 1953 2 Sheets-Sheet l l M- 70 66 ll #64 62 l l=\ I gg L 6/ FeoM GOMMON 5uMP g 66 g g, I H I /6 INVENTQR.

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H. G. UPTON Sept. 13, 1955 FUEL SYSTEM FOR TWO-CYCLE INTERNAL COMBUSTION ENGINES Filed April 27, 1953 2 Sheets-Sheet 2 INVENTOR. llAEkl fi UPTOA/ United States Patent FUEL SYSTEM FQR TWO-CYCLE INTERNAL COMBUSTIGN ENGINES Harr G. Upton, Marysville, "was.

Application April 27, 1953, Serial No. 351,226

16 Claims. (Cl. 123-419 This invention relates to an improved fuel system for two-cycle internal combustion engines, and more particularly to a means for reducing the fuel consumption and improving the performance of such engines. The invention is herein illustratively described by reference to its presently preferred form as applied to a conventional outboard motor of modern design, but it will be appreciated that certain modifications and changes may be made therein without departing from the characterizing features of the invention.

Unburned low-grade fuel unavoidably accumulates in the crank case of a two-cycle engine and in conventional outboard motors is discharged as waste through the exhaust system. At low speeds, the percentage of fuel lost in this manner is disturbingly high since a comparatively rich carburetor mixture is used in order to maintain smooth operation. There is also some wastage of fuel from this cause at high operating speeds because of the overly rich mixture ratio, which can be minimized, but usually is not, by making a manual adjustment of the mixture control each time the speed is changed appreciably. In the case of outboard motors of large size in particular the wastage of fuel through the crank case is very undesirable. Not only does it cause a great loss of economy but it gives rise to the difficult problem of accommodating in a small outboard motor boat the considerable weight and bulk of gasoline sufficient for trips.

It is understood that efforts have been made in the past to recover and use this waste low-grade fuel accumulating in the crank case of two-cycle engines by returning such fuel either to the fuel tank, the carburetor bowl or to some interconnecting passage between the two as to mix with the pure high-grade fuel before passage thereof through a carburation jet. These attempts have not been successful, however, apparently because the admixture of low-grade base fuel directly with the pure high-grade form unbalances the carburetor mixture, and the amount of unbalance varies with engine speed.

The present invention provides a means for successfully recovering and using this low-grade fuel in a continuous process during operation of a two-cycle engine. A first feature of the system includes the provision of an auxiliary carburetor nozzle to which the usually wasted low-grade fuel is delivered through a recovery or scavenge line connected to a common sump receiving the discharge of the two crank case drains. A closed recovery system or circuit is thereby formed. When this type of connection is made, however, the partial vacuum of the carburetor is applied to the check valves in the crank case drains. Since this applied vacuum, progressively increasing with engine speed, urges the check valves toward open position, the normal action of these valves is disturbed particularly at high speeds and any differences in the effective sizes or flow restrictions through the two crank case drain passages will be uncompensated. The result in most cases, therefore, will be a badly unbalanced engine and a serious loss of power, especially at higher speeds.

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This tendency toward unbalanced motor operation in the foregoing basic arrangement is overcome by the additional provision of a metering valve in the scavenge line. The control means for such valve is preferably connected to the throttle mechanism to be moved progressively from a maximum open position to a maximum closed position conjointly with progressive adjustment of the throttle in the reverse sense, that is, from a low-speed to a high-speed setting. The action of the metering valve is unique in that the valve opening, hence the scavenge line suction, is greatest when the volume of fuel collecting and required to be withdrawn from the crank case is a maximum. Conversely the valve opening and the suction applied to the crank case check valves is a minimum (preferably zero) when engine speed is a maximum, at which time the amount of crank case accumulation is a minimum or substantially zero so that its discharge or removal is unnecessary, whereas it is necessary or highly desirable to isolate the check valves from the partial vacuum in the carburetor in order to prevent an unbalanced engine. The efiect of such a metering valve in the novel fuel saving system therefore is uniquely dovetailed with the requirements for an efficient engine employing the invention.

In effect, therefore, the present invention permits establishing a carburetor setting which is economically efficient at high operating speeds without depriving the motor of a sufficiently rich mixture for smooth operation at low speeds, since a progressive reduction of speed results in a corresponding increase of fuel collecting in the crank case and recovered therefrom for supplementing the regular fuel supply.

In actual fuel consumption tests conducted at low speeds a standard factory model 25 horsepower conventional outboard motor operated under ordinary conditions was found capable of operating for a certain period of time on a measured quantity of fuel, while a similar outboard motor modified to incorporate the present invention was found to operate from two to three times as long on the same quantity of fuel under the same test conditions. Moreover, there was also a substantial gain in economy, though not as great, at high speeds.

A further feature of the invention closely related to the means for recovering and reusing waste fuel as described above is concerned with maintaining smooth performance in the modified engine accompanying sudden transitions, especially those from high to low speed. When a conventional outboard motor is suddenly throttled down there is some tendency for it to quit or stall for lack of sufficient fuel, depending upon the condition and design of the particular engine. This tendency is considerably increased in the case of an engine incorporating the above-mentioned fuel-saving features since the available supply of waste fuel accumulated in the crank case constitutes a substantial part of the total fuel being burned in the engine at low speeds. Thus while such a modified engine is being operated at high speed, an equilibrium condition exists in which very little waste fuel accumulates in the crank case because the carburetor is set very lean by ordinary standards, and when the throttle is suddenly shifted to a low-speed setting, the amount of supplemental fuel available from crank case accumulation is so small that the engine would tend to quit in the absence of special carryover fuel supply provisions. In view of this, the present invention further provides a means herein sometimes referred to as a deceleration pump actuated conjointly with the throttle mechanism for injecting additional fuel (preferably from the regular carburetor supply) into the engine for a predetermined period of time sufficient to carry it over the lean period during which the supply of waste fuel from the chank case is building up to requirements at the reduced operating speed. An additional advantage of the deceleration pump incidental to its function as a carryover fuel injection means resides in its utility as a means for priming the engine to start readily with little or no choking. By shifting the throttle back and forth one or more timesa corresponding number of charges of fresh fuel from the deceleration pump are injected into the carburetor for priming the engine to start.

These and other features, objects, and advantages of the invention together with certain details of the illustrated form thereof will become more fully evident from the following description with reference to the accompanying drawings.

Figure 1 is a simplified and partly schematic side elevation view of the improved fuel system shown in relation to certain portions of a conventional outboard motor which are illustrated in broken lines.

Figure 2 is a sectional front view at a larger scale showing some of the system components.

Figure 3 is a top view of the illustrative embodiment of the invention and Figure 4 is a side view thereof, certain portions of the mechanism being broken away for clarity in both views.

Figure 5 is a sectional detail of the carburetor passage which shows the preferred location of the auxiliary nozzle.

Figure 1 incorporates an approximate outline of certain major components of the power head of a conventional two-cycle outboard motor of well known modern design. Such components include the cylinder block 10, spark plugs 12 and 14, carburetor bowl 16 and manifold 18, air intake 26, cowling 22, starter 2.4, flywheel 26 and combined steering handle and throttle control 28. While not shown in full, the throttle mechanism includes a throttle actuating link 30 operated by an arm n 32 fixed on a control shaft 34, the shaft being rocked into varying adjusted positions by the throttle control hand grip (not shown) on steering handle 28 in the usual manner. The motor also includes a separate discharge opening or vent (not shown) leading from the base of each section of the crank case, each such discharge opening being connected to one of the crank case drains 3S and 37, respectively. These crank case drains have check valves 39 and 41, respectively, and discharge into a common sump 43. In a conventional engine the discharge from the crank case drains is wasted through the exhaust system of the engine. The purpose of the check valves 39 and 41, which may be of the reed or other type, is to permit the development of operating vacuum and dis charge pressures alternately in the two sections of the crank case independently of each other in the usual manner.

The present invention provides a conduit or scavenge line 36 connected to the common sump 43 for receiving all of the waste fuel discharged into the sump from the two crank case drains 35 and 37. This scavenge line leads from the common sump to the auxiliary carburetor nozzle 38 located in the existing carburetor air duct 18 adjacent to the usual shutter 40. Preferably the nozzle 38, designed to function efficiently with heavy or low-grade fuel, is directed against the shutter so as to help break up or atomize the droplets of somewhat heavy liquid lowgrade fuel discharged from the auxiliary nozzle. The conventional low-speed nozzle 42 and the conventional high-speed nozzle 44 (Figure 5) are located in suitable positions, as is the choke 46. As indicated, the auxiliary nozzle 38 is positioned between the other two nozzles, and on the downstream side of the venturi 47.

A metering valve 48 is placed in the scavenge line 36. As illustrated, the valve casing is in the form of a T (Figure 2). Fuel entering the valve casing through the conduit 36 flows into the tubular valve element 550 rotatably received in the casing. This tubular valve element has a side aperture 52 therein which, in the valves open position, is in registry with the valve discharge passage or port 54. Closure of the valve is effected by swinging of the lever arm 56 which rotates the valve element St) and thereby blocks the valve port 54. A link 58 pivotally connects the valve arm 56 to an actuating lever 60 secured to the control shaft 62. This actuating lever is thereby caused to change position and to alter the setting of the valve 48 accompanying operation of the throttle mechanism. Moreover, the linkage connections are such that the metering valve 48 is fully closed with the throttle in fully open position and such that progressive movement of the throttle mechanism toward the minimum or low-speed setting simultaneously effects a progressive and substantially proportional opening movement of the metering valve.

As a further provision of the invention the complete system in its preferred form also includes a means for injecting fuel into the carburetor supplemental tothat injected through the usual carburetor nozzles and the auxiliary nozzle described above, and to accomplish this result for a carryover period when the engine is suddenly throttled down in speed. Such a means herein sometimes referred to for convenience as a deceleration pump, a term intended to include any equivalent means, comprises the cylinder housing 62 having a central bore 64 in which a piston 66 carried by the piston rod 68 is free to slide longitudinally. A helical compression spring "It? encircling the piston rod in the housing above the piston rests against the bore plug '72 and the back side of the piston to urge the latter downwardly in the bore. The outer end of the piston rod is connected to one end of the lever 74' which is pivoted intermediate its ends on a pin 75.

A lateral projection or arm 74 on the lever 74 is disposed in the path of downward swing of the valve actuating lever 60 which is swung through various adjusted angular positions when the throttle control mechanism is actuated. The arrangement is such that when the throttle mechanism is advanced from a low-speed toward a high-speed setting, the lever projection 74- being contacted by the lever 69 causes the lever '74 to be swung in a direction (clockwise in Figure 4) causing retraction of the piston 66 in the cylinder bore 64 against the increasing pressure of the spring 70.

A fuel line 76 extends between the intake pipe 78 (Figure 2) which opens into the carburetor bowl, and the base opening 61 in the cylinder housing 62. Upward movement of the piston 66 in the cylinder bore 64 effected by the above-described action of the lever 60 on lever 74 causes fresh liquid fuel to be withdrawn from the carburetor bowl and charge the lower portion of the cylinder bore 6 This influx of fresh fuel into the cylinder bore flows past a check valve 82 housed in the fitting 8d, securing the line 76 to the cylinder housing. Another fuel line 8 extends from a side opening 36 in the cylinder housing to a T fitting 88 located in the scavenge line 36 preferably between the metering valve and the common sump. The fuel line 84 is connected to the cylinder housing by a fitting 90 containing the check valve 92. The springs in the respective check valves 82 and 92 are of a stiffness which prevents carburetor suction in the scavenge line 36 from drawing fresh fuel past the check valves and into the scavenge line. Because of the interposition of the metering valve between the carburetor noZZle 33 and the T fitting 83 the actual suction applied to the check valves 82 and 92 tending to draw fuel past them, is progressively cut off as speed increases, since the metering valve is being progressively closed. However, when the piston 66 is moved downwardly in the cylinder bore 64 by speed-reducing movement of the engine throttle the check valve 92 freely opens and the contents of the cylinder are discharged through the line 34 into the scavenge line 36 and are drawn by carburetor suction through the metering valve 48 and into the auxiliary nozzle 38 for dis charge into the carburetor. This discharge action of the deceleration pump is effected by the spring 70 at a predetermined rate which is independent of the rate of speed-reducing movement of the throttle mechanism, assuming such movement to be faster than a certain minimum so as to completely release the pump control elements comprising lever 74 and piston rod 68. If the engine is throttled down at a slower rate, the arm 60 of course blocks swinging of lever 74 at the maximum possible rate achievable by the expansion of the spring 70; however, the carryover fuel requirements of the engine from the deceleration pump are correspondingly less when the engine is throttled down at a slower rate.

By proper design of the orifices through or past check valve 92 as well as the resistance to flow through the line 84, the piston-eifected discharge of fresh fuel from the deceleration pump occurs over a suflicient period of time to sustain engine operation at the suddenly reduced speed until the accumulation of fuel in the crank case is suificient to supplement fully the regular supply of fresh fuel provided through jets 42 and 4'4. It is advantageous to provide a unilateral one-way actuating arrangement be tween the levers 60 and 74 as illustrated for the further reason that any damage to the mechanical parts of either the piston-actuating mechanism associated with the deceleration pump or to related parts caused by abusive handling of the motor will not tend to bind the throttle mechanism.

The drawings, and especially Figures 2, 3 and 4, show a sufiicient amount of detail of the components employed by the present invention in an actual case to demonstrate the simplicity and convenience of installing these additional parts upon a conventional motor if desired. To those familiar with the present day conventional 25 horsepower outboard motors of a certain manufacturer, for instance, it will be seen that these additions may be made without requiring material alterations in the basic parts of the motor and that they may be made without otherwise interfering with the existing mechanism nor unduly cramping the space inside the cowling 22.

In operation of the improved fuel saving system, the lever 60 assumes a position which is determined directly by the setting of the engine throttle mechanism. If the throttle is set for idling speed, the lever 60 positions the metering valve 48 in its maximum open position so that full suction of the carburetor applied to the scavenge line 36 draws the accumulation of fuel in the common sump 43 into the carburetor for discharge through the nozzle 38. All of the low-grade fuel recovered from the crank case is injected into the carburetor and none is wasted, since the common sump 43 is otherwise sealed off. In other words, there is no discharge from the crank case drains into the exhaust system of the engine in the usual manner. At low-speed settings, therefore, the metering valve is in maximum open position and the maximum amount of recovered fuel from the crank case is returned to the carburetor to provide the necessary supplement to the fresh fuel injected through the regular nozzles 42 and 44. Thus the effective openings of these latter two nozzles may be reduced to a fixed minimum without depriving the engine of a sufiiciently rich mixture for smooth operation at low speeds.

As the engine throttle is moved progressively toward a high-speed setting, the arm 60 is swung upward at a corresponding rate. This progressively closes the metering valve 48 and furnishes increasing isolation of the check valves 39 and 41 from the progressively increasing carburetor suction. This progressive closure of the metering valve does not block the flow of recovered fuel to the nozzle 38 inasmuch as the amount of accumulated fuel in the crank case progressively decreases as engine speed increases. When the maximum speed setting is reached, the metering valve is preferably in the fully closed position so as to completely isolate the check valves 39 and 41 from carburetor suction, and thereby permit these valves to function in their normal manner. It is to be noted,

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however, that closure of the metering Valve 48 under those conditions does not cause the crank case nor the sump 43 to load up with an accumulation of low-grade fuel because such accumulation at high speeds is substantially zero when the mixture ratio controls for the regular carburetor nozzles 42 and 44 are properly adjusted. In this regard the present invention permits a very lean carburetor mixture setting to be made with respect to both of the nozzles 42 and 44 so that at maximum engine speed the total fuel supply is just sufficient for combustion purposes whereas at minimum or idling speed the necessary supplement to the mixture richness is supplied wholly by recovery of low-grade fuel accumulating in the crank case.

When the throttle mechanism is moved from a lowspeed to a high-speed setting, the lever swings downward and thereby operates the lever 74 to retract the piston 66 in the bore 64 and draw fresh fuel into the lower portion of the bore 64 from the carburetor bowl. Thereafter when the throttle setting is reduced, upward movement of the lever 60 frees the lever 74 to permit the spring '70 to expand and thereby advance the piston 66 in the cylinder bore to discharge this supply of fresh fuel into the scavenge line 36. This discharge, protracted due to resistance to flow, continues long enough to carry the engine over the lean period during which low-grade fuel begins to accumulate in the crank case at the reduced speed.

Moreover, by working the throttle mechanism back and forth one or more times before starting the engine, the piston 66 is caused to move up and down in the cylinder bore 64 and one or more charges of fresh fuel are thereby injected into the carburetor through the auxiliary nozzle 38. This primes the engine and greatly facilitates starting thereof even without use of the choke. Accordingly the deceleration pump comprising the piston 66 and cylinder housing 62 has a two-fold purpose or advantage.

It is desired to reemphasize that a properly adjusted carburetor in the present system yields maximum efiiciency of the engine at all speeds without any readjustments. Such a carburetor setting is normally made as lean as possible for efficient operation at high speeds, reliance being placed upon the recovery of crank case fuel in increasing quantities to supplement richness of the carburetor mixture as speed is progressively decreased.

I claim as my invention:

1. In a fuel system for a two-cycle internal combustion engine having carburetor means for the supply of fresh fuel to the engine cylinders, the combination comprising supplemental carburetion means including an auxiliary carburetor nozzle arranged for the supply of supplemental fuel to the engine cylinders, means associated with the crank case drains of the engine to receive low-grade fuel discharged therefrom during engine operation, conduit means interconnecting said receiving means and said auxiliary nozzle such that carburetor suction is applied to said receiving means to draw the low-grade fuel therefrom for discharge through said auxiliary nozzle continuously during engine operation and thereby supplement the fresh fuel supply with such low-grade fuel, metering valve means in the conduit means, an operating connection to said metering valve means from the throttle mechanism of the engine for progressively closing such valve means automatically accompanying speed-increasing movement of the engine throttle, whereby carburetor suction applied F through the conduit means to the engines check valves associated with the crank case drains is progressively cut off with such throttle movement.

2. The fuel system combination defined in claim 1, and deceleration pump means, means to supply fresh fuel thereto, an operating connection to said deceleration pump means from the engines throttle mechanism for automatically priming said pump means from said fresh fuel supply by speed-increasing throttle movement and effectingdischarge of said pump means accompanying speedreducing throttle movement, and conduit means connected for carrying the discharge of said deceleration pump means to the auxiliary carburetor nozzle.

3. The fuel supply system combination defined in claim 2, wherein the deceleration pump means comprises a cylinder, a piston movable in said cylinder by the deceleration pump operating connection to effect charging and discharging thereof, a spring opposing cylindercharging movement of said piston and operable upon release of said piston to effect cylinder-discharging movement thereof, said latter operating connection being of a unilateral type whereby sudden speed-reducing throttle movement releases said piston for independent movement thereof impelled by said spring.

4. In a fuel system for a two-cycle internal combustion engine having carburetor means for the supply of fresh fuel to the engine cylinders, the combination comprising supplemental carburetion means including an auxiliary carburetor nozzle arranged for the supply of supplemental fuel to the engine cylinders, means associated with the crank case drains of the engine to receive low-grade fuel discharged therefrom during engine operation, conduit means interconnecting said receiving means and said auxiliary nozzle such that carburetor suction is applied to said receiving means to draw the low-grade fuel therefrom for discharge through said auxiliary nozzle continuously during engine operation and thereby supplement the fresh fuel supply with such low-grade fuel, deceleration pump means, means to supply fresh fuel thereto, an operating connection to said deceleration pump means from the engines throttle mechanism for automatically priming said pump means from said fresh fuel supply by speedincreasing throttle movement and effecting discharge of said pump means accompanying speed-reducing throttle movement, and conduit means connected for carrying the discharge of said deceleration pump means to the auxiliary carburetor nozzle.

5. The fuel supply system combination defined in claim 4, wherein the deceleration pump means comprises a cylinder, a piston movable in said cylinder by the deceleration pump operating connection to effect charging and discharging thereof, a spring opposing cylindercharging movement of said piston and operable upon release of said piston to effect cylinder-charging movement thereof, said latter operating connection being of a unilateral type whereby sudden speed-reducing throttle movement releases said piston for independent movement thereof impelled by said spring.

6. A fuel system for two-cycle internal combustion engines comprising in combination with an engine carburetor having basic nozzle means for the injection of fresh highgrade fuel into such carburetor, an auxiliary nozzle adapted for the injection of relatively low-grade fuel into such carburetor, means connected to the crank case drains of the engine for reception of the relatively lowgrade fuel accumulating in the crank case and discharged therefrom past the usual check valves in such drains, means continuously delivering such relatively low-grade fuel collecting in said sump to said auxiliary carburetor nozzle as supplemental fuel, whereby a relatively lean mixture ratio of fresh fuel injected by said basic nozzle means is permitted, and valve means associated with the low-grade fuel delivery means and movable between open and closed positions to vary the carburetor suction applied to the sump through such delivery means.

7. The fuel system defined in claim 6, wherein the valve means includes a control element operatively connected to the engines throttle mechanism to effect full closure of said valve means in the maximum speed setting of said throttle mechanism and to open said valve means progressively accompanying speed reducing movement of such throttle mechanism.

8. The fuel system defined in claim 7, and carryover fuel injection means actuated by the throttle mechanism of the engine, said injection means being connected between the fresh fuel supply of the engine and the auxiliary carburetor nozzle and being operable to deliver a charge of fresh fuel to such nozzle accompanying speed-reducing movement of the throttle mechanism.

9. The fuel system defined in claim 8, wherein the carryover fuel injection means comprises a charge and discharge control element and a unilateral actuating connection between such element and the engines throttle mechanism operable to effect charging of such fuel injection means with fresh fuel accompanying speed-increasing throttle movement while releasing said injection means control element accompanying relatively rapid speed-reducing throttle movement, said injection means including a spring progressively loaded by charging movement of said control element and effecting discharge movement of such element upon said release thereof.

10. A fuel system for a two-cycle internal combustion engine comprising carburetor nozzle means normally operated with a fixed relatively lean mixture ratio setting suited for supplying substantially the entire fuel requirements of the engine for efficient combustion at maximum engine speed, auxiliary carburetor nozzle means, means collecting the discharge of low-grade fuel from the crank case drains, and means conveying such discharged fuel to said auxiliary nozzle means at a rate which varies inversely with engine speed.

11. A fuel system for a two-cycle internal combustion engine comprising carburetor nozzle means normally operated with a fixed relatively lean mixture ratio setting suited for supplying substantially the entire fuel requirements of the engine for efficient combustion at maximum engine speed, auxiliary carburetor nozzle means, means collecting the discharge of low-grade fuel from the crank case drains, and throttle-controlled means conveying such discharged fuel to said auxiliary nozzle means at a rate which varies inversely with engine speed.

12. The fuel supply system defined in claim 1 1, wherein the conveying means comprises conduit means establishing direct communication between the crank case drains and the auxiliary nozzle, and a metering valve in the conduit controlled by the throttle mechanism of the engine, said valve being closed by the throttle mechanism in the maximum speed setting thereof and progressively opened by such mechanism accompanying speed-reducing movement thereof.

13. A fuel saving system for two-cycle internal combustion engines comprising carburetor means normally operated with a fixed relatively lean mixture ratio setting suited for supplying substantially the entire fuel requirements of the engine for efficient combustion at maximum engine speed, auxiliary carburetor means adapted for efiicient combustion of low-grade fuel, conduit means collecting and returning to said auxiliary carburetor means the low-grade fuel discharge from the crank case drains of the engine by carburetor suction and valve means in series with such conduit controlled by the engines throttle mechanism isolating said crank case drains from said carburetor suction increasingly with increasing speed settings of the throttle mechanism.

14. The fuel saving system defined in claim 13, and carryover fuel injection means conected to said auxiliary carburetor means and controlled by movement of the engines throttle mechanism to inject additional fuel into the carburetor automatically at a predetermined rate and for a predetermined period commencing with and following sudden speed-reducing throttle movement, whereby additional fuel is supplied to the engine during such period pending accumulation of low-grade fuel in the crank case at the reduced speed.

15. In a fuel supply system for an internal combustion engine, deceleration-carryover fuel injection means supplied with fuel from the engines supply and comprising a charge and discharge control element connected to the engines throttle mechanism to be actuated by speed-increasing movement of such mechanism for charging of said fuel injection means, the connection between such mechanism and said element being a unilateral operating connection whereby speed-decreasing movement of such throttle mechanism permits discharge movement of said control element at a slower rate than such speed-decreasing movement, and spring means effecting discharge movement of said control element.

16. A fuel saving system for a two-cycle internal combustion engine comprising carburetor means supplying fresh fuel to the engine cylinders, conduit means conducting low-grade fuel discharged from the crank case drains to the engine cylinders as a supplemental source of fuel, and carry-over fuel supply means connected to the throttle 10 mechanism of the engine and operated by speed-reducing movement of such mechanism for increasing the supply of fresh fuel to the engine cylinders for a limited period of time commencing with such speed-reducing movement of the throttle mechanism.

Edwards Nov. 30, 1920 Smith May 25, 1948 

